Hydrocharitaceae

{{Short description|Family of aquatic plants}} {{Automatic taxobox | image = HydrocharisMorsus-ranae2.jpg | image_caption = Common frogbit, ''Hydrocharis morsus-ranae'' | taxon = Hydrocharitaceae | authority = Juss.<ref name="APGIII">{{Cite journal |last=Angiosperm Phylogeny Group |year=2009 |title=An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III |journal=Botanical Journal of the Linnean Society |volume=161 |issue=2 |pages=105–121 |doi=10.1111/j.1095-8339.2009.00996.x |doi-access=free |hdl=10654/18083 |hdl-access=free }}</ref> | subdivision_ranks = Genera | subdivision = *''Appertiella'' {{small|C.D.K.Cook & L.Triest}} *''Blyxa'' {{small|Noronha ex Thouars}} *''Elodea'' {{small|Michx.}} *''Enhalus'' {{small|Rich.}} *''Halophila'' {{small|Thouars}} *''Hydrilla'' {{small|Rich.}} *''Hydrocharis'' {{small|L.}} *''Lagarosiphon'' {{small|Harv.}} *''Najas'' {{small|L.}} *''Nechamandra'' {{small|Planch.}} *''Ottelia'' {{small|Pers.}} *''Stratiotes'' {{small|L.}} *''Thalassia'' {{small|Banks & Sol. ex K.D.Koenig}} *''Vallisneria'' {{small|P.Micheli ex L.}} |subdivision_ref = <ref name = powo>{{cite web |title=Hydrocharitaceae Juss. |url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30013086-2 |website=Plants of the World Online |publisher=Royal Botanic Gardens, Kew |access-date=25 May 2025}}</ref> |synonyms = Najadaceae {{small|Juss.}} |synonyms_ref = <ref name = powo/> | range_map = }}

'''Hydrocharitaceae''' is a flowering plant family which includes 14 accepted genera<ref name = powo/> and a total of ca 135 known species (Christenhusz & Byng 2016<ref name="Christenhusz-Byng2016">{{cite journal |author1=Christenhusz, M. J. M. |author2=Byng, J. W. | year = 2016 | title = The number of known plants species in the world and its annual increase | journal = Phytotaxa | volume = 261 | pages = 201–217 | url = http://biotaxa.org/Phytotaxa/article/download/phytotaxa.261.3.1/20598 | doi = 10.11646/phytotaxa.261.3.1 | issue = 3 | publisher = Magnolia Press |bibcode=2016Phytx.261..201C | doi-access = free }}</ref>). The family holds a number of species of aquatic plants, including tape-grass, the well-known Canadian waterweed, and frogbit.

The family includes both freshwater and marine aquatics. They are found throughout the world in a wide variety of habitats, but are primarily tropical.

== Description == The species are annual or perennial, with a creeping monopodial rhizome with the leaves arranged in two vertical rows, or an erect main shoot with roots at the base and spirally arranged or whorled leaves. The leaves are simple and usually found submerged, though they may be found floating or partially emerse. As with many aquatics they can be quite variable in shape – from linear to orbicular, with or without a petiole, and with or without a sheathing base.

The flowers are arranged in a forked, spathe-like bract or between two opposite bracts. They are usually irregular, though in some case they may be slightly irregular, and either bisexual or unisexual. The perianth segments are in 1 or 2 series of 2–3 free segments; the inner series when present are usually showy and petal-like. Stamens 1–numerous, in 1 or more series; the inner ones sometimes sterile. pollen grains are globular and free but in the marine genera (''Thalassia'' and ''Halophila'') – the pollen grains are carried in chains, like strings of beads. The ovary is inferior with 2–15 united carpels containing a single locule with numerous ovules on parietal placentas which either protrude nearly to the centre of the ovary or are incompletely developed. Fruits are globular to linear, dry or pulpy, dehiscent or more usually indehiscent and opening by decay of the pericarp. Seeds are normally numerous with straight embryos and no endosperm.

Pollination can be extremely specialised.

The most recent phylogenetic treatment of the family recognizes four subfamilies.<ref>{{citation | title = A reappraisal of phylogenetic relationships in the monocotyledon family Hydrocharitaceae (Alismatidae) | year = 2006 | last1 = Les DH | first1 = DH | last2 = Moody | first2 = ML | last3 = Soros | first3 = CL | journal = Aliso | volume = 22 | pages = 211–230 | doi = 10.5642/aliso.20062201.18 | doi-access = free }}</ref> * Subfamily Anacharioideae (''Appertiella'', ''Blyxa'', ''Egeria'', ''Elodea'', ''Lagarosiphon'' and ''Ottelia'') * Subfamily Hydrilloideae (''Enhalus'', ''Halophila'', ''Hydrilla'', ''Maidenia'', ''Najas'', ''Nechamandra'', ''Thalassia'' and ''Vallisneria''). * Subfamily Hydrocharitoideae (''Hydrocharis'', ''Limnobium'') * Subfamily Stratiotoideae (''Stratiotes'')

{{clade|style=font-size:100%;line-height:100% |label1=Hydrocharitaceae |1={{clade |1={{clade |1={{clade |label1=Hydrilloideae |1={{clade |1={{clade |1={{clade |1={{clade |1=Enhalus |2=Thalassia }} |2=Halophila }} |2={{clade |1={{clade |1={{clade |1=Vallisneria }} |2=Nechamandra }} |2=Hydrilla }} }} |2=Najas }} |label2=Hydrocharitoideae |2={{clade |1=Limnobium |2=Hydrocharis }} }} |label2=Anacharioideae |2={{clade |1={{clade |1={{clade |1={{clade |1={{clade |1=Elodea }} |2=Egeria }} |2=Appertiella }} |2={{clade |1=Ottelia |2=Blyxa }} }} |2=Lagarosiphon }} }} |label2=Stratiotoideae |2=Stratiotes }} }}

[[File:Hydrilla verticillata is it- in Hyderabad W2 IMG 8305.jpg|thumb|''Hydrilla verticillata'']] [[File:Ottelia alismoides W IMG 0915.jpg|thumb|''Ottelia alismoides'']]

== Uses == Some species have become established ornamental plants, and subsequently serious weeds in the wild (especially ''Egeria'', ''Elodea'' and ''Hydrilla'').

== Genera == 14 genera are currently accepted.<ref name = powo/> {{div col|colwidth=11em}} *''Appertiella'' {{small|C.D.K.Cook & L.Triest}} *''Blyxa'' {{small|Noronha ex Thouars}} *''Elodea'' {{small|Michx.}} (synonyms ''Apalanthe'' {{small|Planch.}} and ''Egeria'' {{small|Planch.}}) *''Enhalus'' {{small|Rich.}} *''Halophila'' {{small|Thouars}} *''Hydrilla'' {{small|Rich.}} *''Hydrocharis'' {{small|L.}} (synonym ''Limnobium'' {{small|Rich.}}) *''Lagarosiphon'' {{small|Harv.}} *''Najas'' {{small|L.}}<ref name="APGIII" /><ref>{{citation | doi = 10.1007/BF02524931 | title = Phylogeny of the family Hydrocharitaceae inferred from rbcL and matK gene sequence data | year = 1997 | last1 = Tanaka | first1 = Norio | last2 = Setoguchi | first2 = Hiroaki | last3 = Murata | first3 = Jin | journal = Journal of Plant Research | volume = 110 | issue = 3 | pages = 329 | bibcode = 1997JPlR..110..329T | s2cid = 10939773 }}</ref><ref name="les">{{citation | title = Phylogenetic studies in Alismatidae, II: evolution of marine angiosperms (seagrasses) and hydrophily | year = 1997 | last1 = Les | first1 = DH | last2 = Cleland | first2 = MA | last3 = Waycott | first3 = M | journal = Systematic Botany | volume = 22 | issue = 3 | pages = 443 | doi=10.2307/2419820| jstor = 2419820 | bibcode = 1997SysBo..22..443L }}</ref><ref>[https://web.archive.org/web/20000712110354/http://www.ars-grin.gov/cgi-bin/npgs/html/gnlist.pl?561 Genera of Hydrocharitaceae], ''GRIN Taxonomy for Plants''</ref> *''Nechamandra'' {{small|Planch.}} *''Ottelia'' {{small|Pers.}} *''Stratiotes'' {{small|L.}} *''Thalassia'' {{small|Banks & Sol. ex K.D.Koenig}} *''Vallisneria'' {{small|P.Micheli ex L.}} (synonym ''Maidenia'' {{small|Rendle}}) {{div col end}}

{| class="wikitable" style="margin:1em auto;" |+ Genera crosses (Hydrocharitaceae) ! scope="col" | Kubitzki (ed. 1998<ref>Kubitzki (ed.) 1998. ''The families and genera of vascular plants, vol 4, Monocotyledons: Alismatanae and Commelinanae (except Gramineae).'' Springer-Verlag, Berlin.</ref>) ! scope="col" | data.kew<ref>Vascular Plant Families and Genera. List of genera in family HYDROCHARITACEAE (accessed 2016-06-02) http://data.kew.org/cgi-bin/vpfg1992/genlist.pl?HYDROCHARITACEAE</ref> ! scope="col" | APWeb (mobot.org)<ref>VASCULAR PLANT FAMILIES and GENERA. List of Genera in HYDROCHARITACEAE. (accessed 2016-06-02) http://www.mobot.org/mobot/research/apweb/genera/hydrocharitaceaegen.html</ref> ! scope="col" | Watson & Dallwitz (delta-intkey)<ref>Watson & Dallwitz. Hydrocharitaceae. ''The families of flowering plants.'' http://delta-intkey.com/angio/www/hydrocha.htm {{Webarchive|url=https://web.archive.org/web/20090408100859/http://delta-intkey.com/angio/www/hydrocha.htm |date=2009-04-08 }}</ref> |- ! colspan="4" | Hydrocharitaceae |- | 1. ''Ottelia'' || ''Ottelia'' Pers. (including ''Beneditaea'' Toledo, ''Boottia'' Wall.) (excludes ''Oligolobos'' Gagnep.) || ''Ottelia'' Persoon (including ''Beneditaea'' Toledo, ''Boottia'' Wallich, ''Oligolobos'' Gagnepain, ''Xystrolobos'' Gagnepain) || ''Ottelia'' |- | 2. ''Stratiotes'' || ''Stratiotes'' L. || ''Stratiotes'' L. || ''Stratiotes'' |- | 3. ''Hydrocharis'' || ''Hydrocharis'' L. || ''Hydrocharis'' L. || ''Hydrocharis'' |- | 4. ''Limnobium'' || ''Limnobium'' Rich. (including ''Hydromystria'' G.Mey. || ''Limnobium'' Richard (including ''Hydromystria'' G. Meyer) || ''Limnobium'' |- | 5. ''Blyxa'' || ''Blyxa'' Noronha ex Thouars (excludes ''Enhydrias'' Ridl.) || ''Blyxa'' Richard (including ''Enhydrias'' Ridley) || ''Blyxa'' |- | 6. ''Apalanthe'' || ''Apalanthe'' Planch. || (in ''Elodea'' Michaux) || ''Apalanthe'' |- | 7. ''Egeria'' || ''Egeria'' Planch. || ''Egeria'' Planchon || ''Egeria'' |- | 8. ''Elodea'' || ''Elodea'' Michx. (including ''Anacharis'' Rich., ''Udora'' Nutt.) || ''Elodea'' Michaux (including ''Anacharis'' Richard, ''Apalanthe'' Planchon, ''Hydora'' Besser, ''Philotria'' Rafinesque, ''Serpicula'' Pursh, ''Udora'' Nuttall) || ''Elodea'' |- | 9. ''Hydrilla'' || ''Hydrilla'' Rich. || ''Hydrilla'' Richard || ''Hydrilla'' |- | 10. ''Appertiella'' || ''Appertiella'' C.D.K.Cook & Triest || ''Appertiella'' C. D. K. Cook & Triest || ''Appertiella'' |- | 11. ''Lagarosiphon'' || ''Lagarosiphon'' Harv. || ''Lagarosiphon'' Harvey || ''Lagarosiphon'' |- | 12. ''Nechamandra'' || ''Nechamandra'' Planch. || ''Nechamandra'' Planchon || ''Nechamandra'' |- | 13. ''Maidenia'' || ''Maidenia'' Rendle || ''Maidenia'' Rendle || ''Maidenia'' |- | 14. ''Vallisneria'' || ''Vallisneria'' L. || ''Vallisneria'' L. || ''Vallisneria'' |- | 15. ''Enhalus'' || ''Enhalus'' Rich. || ''Enhalus'' Richard || ''Enhalus'' |- | 16. ''Thalassia'' || ''Thalassia'' Banks ex C.Koenig || ''Thalassia'' C. Koenig || ''Thalassia'' |- | 17. ''Halophila'' || ''Halophila'' Thouars || ''Halophila'' Thouars || ''Halophila'' |- | (in ''Najas'', Najadaceae) || ''Najas'' L. || ''Najas'' L. || (in ''Najas'', Najadaceae) |- | (name not found) || ''Enhydrias'' Ridl. || (in ''Blyxa'', Hydrocharitaceae) || (name not found) |- | (name not found) || ''Oligolobos'' Gagnep. || (in ''Ottelia'', Hydrocharitaceae) || (name not found) |- ! colspan="4" | Najadaceae |- | 1. ''Najas'' || (in ''Najas'', Hydrocharitaceae) || (in ''Najas'', Hydrocharitaceae) || ''Najas'' |}

== References == {{Reflist|32em}}

== External links == *{{Commons category-inline}} *{{Wikispecies-inline}} *{{Cite EB1911 |wstitle=Hydrocharideae |volume=14 |page=112| short=1}}

{{Angiosperm families}} {{Authority control}} {{Taxonbar|from=Q156029}}

Category:Hydrocharitaceae Category:Aquatic plants Category:Alismatales families Category:Taxa described in 1789 Category:Taxa named by Antoine Laurent de Jussieu